1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * (C) Copyright 2016 4 * Olliver Schinagl <oliver@schinagl.nl> 5 */ 6 7 #include <ctype.h> 8 #include <stdbool.h> 9 #include <stdint.h> 10 #include <stdio.h> 11 #include <stdlib.h> 12 #include <string.h> 13 #include <u-boot/crc.h> 14 15 #define ARP_HLEN 6 /* Length of hardware address */ 16 #define ARP_HLEN_ASCII (ARP_HLEN * 2) + (ARP_HLEN - 1) /* with separators */ 17 #define ARP_HLEN_LAZY (ARP_HLEN * 2) /* separatorless hardware address length */ 18 19 uint8_t nibble_to_hex(const char *nibble, bool lo) 20 { 21 return (strtol(nibble, NULL, 16) << (lo ? 0 : 4)) & (lo ? 0x0f : 0xf0); 22 } 23 24 int process_mac(const char *mac_address) 25 { 26 uint8_t ethaddr[ARP_HLEN + 1] = { 0x00 }; 27 uint_fast8_t i = 0; 28 29 while (*mac_address != '\0') { 30 char nibble[2] = { 0x00, '\n' }; /* for strtol */ 31 32 nibble[0] = *mac_address++; 33 if (isxdigit(nibble[0])) { 34 if (isupper(nibble[0])) 35 nibble[0] = tolower(nibble[0]); 36 ethaddr[i >> 1] |= nibble_to_hex(nibble, (i % 2) != 0); 37 i++; 38 } 39 } 40 41 for (i = 0; i < ARP_HLEN; i++) 42 printf("%.2x", ethaddr[i]); 43 printf("%.2x\n", crc8(0, ethaddr, ARP_HLEN)); 44 45 return 0; 46 } 47 48 void print_usage(char *cmdname) 49 { 50 printf("Usage: %s <mac_address>\n", cmdname); 51 puts("<mac_address> may be with or without separators."); 52 puts("Valid seperators are ':' and '-'."); 53 puts("<mac_address> digits are in base 16.\n"); 54 } 55 56 int main(int argc, char *argv[]) 57 { 58 if (argc < 2) { 59 print_usage(argv[0]); 60 return 1; 61 } 62 63 if (!((strlen(argv[1]) == ARP_HLEN_ASCII) || (strlen(argv[1]) == ARP_HLEN_LAZY))) { 64 puts("The MAC address is not valid.\n"); 65 print_usage(argv[0]); 66 return 1; 67 } 68 69 if (process_mac(argv[1])) { 70 puts("Failed to calculate the MAC's checksum."); 71 return 1; 72 } 73 74 return 0; 75 } 76